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Home >> Porsche >> 1987 >> 944 Base, Automatic >> Repair and Diagnosis >> Brakes >> Traction Control >> Anti-Lock Brake System >> Testing >> Program Switch Positions 20, 21 & 22 >> Additional Operations
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Additional Operations

  1. Operating sequence must be maintained when performing these tests.
    • Select test (program switch position).
    • Select channel (wheel).
    • Set brake force to 450 lbs. (2000 N) with foot.
    • Press "LED" button with brief time delay (about .5 seconds).
    • Press "LED" button until test stand display stops. Integral tester program runs several seconds. The Lamp 2 (Red) light should not come on during test. If it does, repeat test with engine running. Wait about 20 seconds before continuing or repeating test. Integral tester program must be run off.
  2. Brake line mix-up test.
    • Drive front wheels of vehicle on brake test stand.
    • Select PROGRAM SWITCH POSITION 20 and press position "5.2" for front left wheel. Switch on left front brake roller.
    • Operate brake pedal until brake force display on brake test stand is 450 lbs. (2000 N).
    • Press "LED" button.
    • Pressure must build up for left front wheel.
    • Perform same test on right front wheel.
    • Press "VR" button and switch on front right brake roller only.
  3. Hydraulic unit front axle test.
    • Parking brake applied.
    • Select test.
    • Select wheel (left front or right front).
    • Switch on both brake rollers.
    • Apply about 450 lbs. (2000 N) brake force on wheel just being tested with brake pedal and hold constant during test. NEVER use a brake pedal winch to adjust brake force.
    • Deviation in brake force display between left and right must not exceed 112 lbs. (500 N).
    • Press "LED" button until test stand display stops and value has been read (time is about 6 seconds).
    • Check for constant brake force during test on the wheel running along. Pedal travel may change. Slight brake force change is permissible, but influences display.
    • Perform PROGRAM SWITCH POSITIONS 20, 21 & 22 on both wheels separately.
  4. Hydraulic unit rear axle test.
    • Drive rear wheels of vehicle on brake test stand.
    • Select test.
    • Press rear axle button.
    • Switch on both brake rollers.
    • Run engine (brake force boost will be effective and makes braking easier).
    • Apply 450 lbs. (2000 N) brake force on wheel just being tested with brake pedal and hold constant during test. NEVER use a brake pedal winch to adjust brake force.
    • Press "LED" button until brake test stand display stops (test time about 6 seconds).
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